Regions
Northwest Coastal.
The Danger Ratings are based on precipitation amounts forecast for the southern portion of the region.
Confidence
Poor - Timing, track, or intensity of incoming weather is uncertain for the entire period
Weather Forecast
Monday: Moderate precipitation with westerly and southwesterly winds 30-50km/h gusting to 90km/h. Freezing levels expected at 600m with alpine temperatures -5 degrees.Tuesday: Light to locally moderate precipitation, temperatures cooling to -7 in the alpine. Winds southwesterly moderate to strong.Wednesday: Light flurries, winds light from the northwest and alpine temperatures -6.
Avalanche Summary
Natural activity isolated to the storm snow to size 1.5. Explosives testing in the past few days north of the Stewart region indicate an avalanche running to size 3.5 in north facing alpine terrain failing in a weak layer of facets near the base of the snowpack.
Snowpack Summary
An additional 15-30cm of snow has fallen accompanied by strong winds. This sits on top of the settled storm accumulations from last week. Alpine and treeline surface snow conditions are variable with buried wind slabs, newly formed wind slabs and areas that are heavily scoured. The mid-pack is gaining strength and is well settled.A November facet/crust layer can be found near the base of the snowpack. We don not have much recent information on this facet/crust interface, so it may be worth digging down yourself to test its reactivity.Total snowpack depth above 1000 m is 160-220 cm deep. Below 1000 m the snowpack shows a sharp transition from 100 cm dropping to 50 cm, and is generally below threshold.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.